Device for eliminating body capacity effects in radio instruments



T. M. HARRIGAN DEVICE FOR ELIMINATING BODY CAPACITY EFFECTS IN RADIO INSTRUMENTS Filed Dec. 20. 1922 I Patented Aug. 14, 1923.

eliminating body capacity efiects in radio instrument without the body v titans ATNT cannon.

THOMAS M. HABRIGAN, OF WOODSTOCK, VERMONT.

DEVICE FOR ELIMINATING BODY CAPACITY EFFECTS IN RADIO INSTRUMENTS.

Application filed December 20, 1922. Serial No. %,089.

To all whom it I concern:

Be it known thgf l f THOMAS M. HARRIGAN, a citizen of the United States, residing at Woodstock, in the county of Windsor and State of Vermont, have invented new and useful Improvements in Devices for Eliminating Body Capacity Effects in Radio Instruments, of which the following is a specification.

This invention relates to a device for instruments, and has for its object to provide a device through the medium of which certain dials employed for adjusting portions of a radio instrument, particularly the condenser, may be rotated while tuning the of the operator influencing the instrument and thereby rendering it difiicult to properly tune the same.

Another object of the invention is to provide a device which may be employed in a manner to obtain a much more delicate adjustment of the dial and portion of the instrument associated therewith than. is possible through the medium of the usual handle provided for the dial.

Theinvention consists in the combination and arrangement of parts set forth in the following specification and particularly pointed out in the claim thereof.

Referring to the drawings:

Figure 1 represents a front elevation of a dial for a radio condenser, a portion of the device embodying the invention being illustrated associated therewith.

Fi 2 is a horizontal sectional elevation as ta on on the line 2-2 of Fig. 1.

Fig. 3 is a view similar to Fig. 2 but illustrating a modified embodiment of the invention.

Like numerals refer to like parts throughout the several views of the drawings.

In the drawings, referring particularly to Figs. 1 and 2, 4 represents a portion of a front panel of a cabinet in which a radio apparatus of any desired construction 1s lo cated and mounted. A dial 5 provided with graduations 6 and also having the usual handle 7, through the medium of which the dial is usually rotated, is located upon the exterior of the panel 4, being fast to a shaft 8 which connects with a condenser well known to those skilled in-the art.

In practically all instances, the dial 5 and handle 7 are either moulded in-one piece,

or are so constructed that they form a single unit and the handle 7 is employed to rotate the dial in adjusting the condenser while tuning the instrument. It has been found, however, that when the hand of the operator grasps the handle 7, and in some instances even before the hand has touched the handle, that a confusing noise is produed which renders an accurate tuning of the instrument difficult.

The device of this invention is, therefore, provided for the purpose of rotating the dial 5 without being obliged to touch the handle 7 and is as follows z-Provided in the panel 4 adjacent to the periphery of the dial 5 is an opening 9 into which may be inserted a friction member 10, preferably constructed of rubber or some other suitable flexible insulating material. A portion 11 of the friction member 10 is conicalshaped and the periphery of said conicalshaped portion engages the periphery of the dial 6 while the apex portion thereof projects through the opening 9 thereby providing means for positioning the friction member relatively to the dial 5. The friction member 10 is rotated through the medium of au'od 12 preferably constructed of insulating material at the outer end of which is located a handle portion 13. The rod 12 is sufficiently long for the operator to grasp the handle 13 thereof without the hand of the operator being sufficiently close to influence the instrument. A shield 14 constructed of suitable insulating material is mounted upon the rod 12 adjacent to the handle portion 13 thereof and said shield also acts to prevent the handof .the operator from influencing the tuning of the instrument.

In tuning a radio instrument, and particularly when manipulating the dial of the condenser, or other portions of the instrument that are influenced by the presence of the body of the operator, the rod 12 is grasped at the handle portion 13 thereof and the conical portion 11 of the friction member 10 is inserted in the openin 9 of the panel 4 and said friction mem r is forced into said opening until the periphery of the conical portion 11 engages the periphery of the dial 5. The rod 12 is then rotated in either direction as required to properly adjust that portion of theradio apparatus that is associated with the dial 5. It will be noted that by using a friction member 10 having a relatively short diam- .eter as compared to the diameter of the dial 5, that a much more delicate adjustment may be obtained than is possible by utilizing the handle 7 of said dial.

It will also be noted that as the friction member 10 is constructed of rubber, that the friction between said member and the periphery of the dial 5 may be increased or decreased as desired according to the pressure upon the rod 12 tending to force the latter into the opening 9.

In Fig. 3 a modified embodiment of the invention is illustrated in which a frusto-conical shaped friction member 15 is permanently secured in an opening 16 in the panel 4 adjacent to the periphery of the dial 5. In this form of the device a rod 17 is provided with a shouldered portion 18 and the friction member 15 is rigidly fastened to said rod with one end thereof abutting against the shouldered portion 18 of said rod while the peripher of said friction member 15 contacts Wit 1 the periphery of the dial 5. The friction member 15 is permanently held within the opening 16 of the panel 4 through the medium of a collar 19 which is detach ably secured upon said rod and said collar bears against the inner surface of the panel 4.- The rod 17 is provided with a handle portion 20 and a shield 21 is furthermore mounted upon said rod adjacent to said handle portion 20. The operation of this embodiment of the invention is exactly the same as previously described in connection with the device illustrated in Figures 1 and 2.

I claim:

A device of the character described comprising, in combination, a panel, a dial rotatably mounted on said panel, said panel being provided with an opening therein located adjacent to the periphery of said dial, a flexible friction member positioned on said panel and projecting into said opening and engaging the periphery of said dial and a rod fast at one end thereof to said friction member and embodying therein a handle portion at the other end thereof.

' In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

THOMAS M. HARRIGAN. Witnesses:

LILLIAN C. Bnuows, JOHN J. COSTELLO. 

